Method for making fluid seals



Oct. 17, 1961 R. N. HAYNIE METHOD FOR MAKING FLUID SEALS Original FiledFeb. 11, 1957 4 Sheets-Sheet 1 Fig.1

Oct. 17, 1961 R. N. HAYNlE 3,004,298

METHOD FOR MAKING FLUID SEALS Original Filed Feb. 11, 1957 4Sheets-Sheet 2 Fig. 7

Oct. 17, 1961 R. N. HAYNIE 3,004,298

METHOD FOR MAKING FLUID SEALS Original Filed Feb. 11, 1957 4Sheets-Sheet 3 Oct. 17, 1961 R. N. HAYNIE 3,004,298

METHOD FOR MAKING FLUID SEALS Original Filed Feb. 11, 1957 4Sheets-Sheet 4 35 :05 I02 '9 I07 5 no l2l Hg. 15

United States Patent 5 Claims. (Cl. 18-59) This invention relates to animportant new method for producing fluid-sealing devices. Thisapplication is a division of application Serial No. 639,276, filedFebruary 1'-1, 1957.

This invention solves many important problems relating to shaft sealsand their manufacture, but it is mpecially valuable in solving theproblem of anchoring a molded elastomeric sealing element to a rigidmember such as a metal casel As a result of solving this problem, a muchbetter product can be provided, and it can be produced at a lower cost.

One object of this invention is to provide an improved anchorage forsecuring a molded elastomeric sealing lip to a rigid member.

Another object of the invention is to provide an improved shaft sealwherein a radially extending annular flange of a case member is providedwith an angularly extending or frusto-conical peripheral portion, andwhere in a synthetic rubber member providing the sealing lip is anchoredsubstantially exclusively to that peripheral portion.

Another object of the invention is to achieve sealing lip anchorage witha minimum amount of the synthetic rubber composing the lip, therebyproviding significant savings in materials and material costs.

Another object of the invention is to provide a very secureanchorage ofa synthetic rubber sealing lip to a reinforcing case structure. Thisanchorage is obtained partly by a novel reforming of an annular edgeportion or tip end of a radially extending annular portion of the metalcase during molding of the rubber lip portion, the rubber portion beingbonded substantially exclusively to this tip end.

Another object of the invention is to provide an improved double-lipseal construction wherein independent action of each lip is achieved.

Another object of the invention is to limit the area where the rubberlip portion is bonded, so that it is only a restricted part of thesurface of the case, and to prevent adhesion of rubber, including flash,to other parts of the case.

Another very important object of the invention is to provide amanufacturing method for making shaft seals from metal cases and moldedrubber parts with substantial elimination of flash from the bondedportion of the rubber member, especially along the radial case member.

Another object of the invention is to provide a more economical methodfor making a shaft seal of the moldedlip type. The present inventionresults in more economical tooling than methods heretofore used,enabling molds having a greater number of cavities per mold than usual,providing molds that may be produced less expensively than heretofore,because of their simplicity, and enabling an increased productioncapacity per mold. As a result, the total labor cost of production canbe considerably reduced.

Another object of the invention is to provide a method forsimultaneously molding a rubber lip portion and bonding it to a rigidcase in a way that makes it possible to use the same mold formanufacturing a variety of "ice sizes of seals having identical sealinglips attached to any of many sizes of rigid cases.

Another object of the invention is to provide a molding process thatleads to improved mold quality.

Another object of the invention is to provide a method for molding arubber sealing lip member and bonding it to a rigid case without havingto use masking or cleanup methods. The new method is insensitive tocement buildup, and metals used as case members may, in fact, bedip-cemented instead of having to be provided with protecting masks, asin the prior art where the cement is sprayed on.

Another object of the invention is to provide a molding method with morepositive pinchoff of rubber than has heretofore been possible.

Another very important object of the invention is to provide greatercertainty that the mold is being filled solidly with rubber, free fromair bubbles. Achievement of this object becomes possible becauseconsiderably more molding pressure can be applied in this process thanhas heretofore been possible in a compression molding process, therebygiving the highest possible density in the rubber molded portion andassuring complete filling of the mold.

Another object is to provide a molding process for fluid sealing lipswherein much wider ranges of molding pressures can be used in theproduction of satisfactory products.

As implied by the foregoing objects, the product of this inventioncomprises a fluid seal of the type having an annular rigid case memberand an annular synthetic rubber sealing member anchored to the casemember by being bonded to it. The case member has an annular radialflange, a peripheral portion of which, in this invention, is turned orbent or formed to provide a frustoconical annular tip to which thesealing lip is bonded. Moreover, the sealing lip portion is preferablynot bonded to any other portion of the case. More specifically, the lipportion is bonded to substantially the entire inner face, the entire endedge and a portion of the outside face of the frusto-conical tip.

The method of the present invention employs a type of compressionmolding. A metal case having a radiallyextending annular flange isinserted around a tapered portion of the mold in a manner which helps tokeep its inner and outer rims concentric. In an internal seal, only theinner rim is seated in the mold. As the mold is closed, a prepared ringof synthetic rubber material (known in the trade as prep) is compressedby the closing mold, so as to flow into the mold cavity. While therubber is flowing but before it reaches the case, a mold member engagesthe case and pushes it down, bending the tip end of the flange againstthe other mold member under very substantial closing pressure. Thus (inan internal seal) the metal case is reformed at the inner pierce (or inan external seal, at the outer periphery). The metal-to-mold contactconsists in effect of a pair of circumferential narrow, almost linear,areas on which is exterted a great force that effectively prevents theleakage of stock. As a result, any excess stock that may be present inthe prep flows around the registration taper instead of flashing at thecase. This excess stock is trimmed off later when the trimming knifeforms the lip edge. Flashing is eliminated; in fact, the mold can beWell overloaded without flashing occurring.

Another way of describing the method briefly is to say that it operateswith a closed stroke, which may be defined as relative movement of themold halves toward each other closing against the metal member to whichthe molded member is to be secured. The stroke is maintained closedbecause of the deformation of the metal during the remainder of the moldmovement.

Other objects and advantages of the invention will appear from thefollowing description of several preferred embodiments thereof.

In the drawings:

FIG. 1 is a front view in elevation of a shaft seal embodying theprinciples of the present invention, looking from the left hand side ofthe seal as shown in FIG. 2.

FIG. 2 is an enlarged fragmentary view in perspective and in sectiontaken along the line 2-2 of FIG. 1.

FIG. 3 is a further enlarged sectional view of the case member andsealing lip of FIG. 2, the sealing lip being shown in this view beforetrimming, with the trim line indicated by a broken line.

. FIG. 4 is a view similar to FIG. 2 of a modified form of seal, alsoembodying the invention but having a somewhat diiferently formed casemember.

FIG. 5 is a view similar to FIG. 2, though on an enlarged scale, ofanother modified form of seal, this one having a double lip. In thisinstance, the invention acts to provide independence of the two lipsfrom each other.

FIG. 6 is a view similar to FIG. 3 showing a portion of the structure ofFIG. 5 before trimming, with the trim lines for the two lips indicatedin broken lines.

FIG. 7 is a view similar to FIG. 2 showing another modified form ofseal. 1

FIG. 8 is another view similar to FIG. 2 showing an external-type seal.

FIGS. 9 through 14 show a molding cycle embodying the method of theinvention as applied to an internal-type seal. These views are inelevation and in section of the left half of the mold.

FIG. 9 shows the initial step in the molding cycle with the case memberin position on the lower half of the mold prior to the closing of theuper half of the mold and with the prep, the prepared ring of syntheticrub ber stock, in place.

FIG. 10 shows the next step in the molding operation with the upper moldhalf coming down toward the lower mold half and beginning to press downon the prep.

FIG. 11 shows the next stage in the molding sequence, with the uppermold half forcing the rubber stock to flow into the mold cavity.

FIG. 12 shows the next step in the sequence, with a rim of the uppermold half contacting the case while a substantial amount of travel stillremains. From here on through FIG. 14 the mold executes its closedstroke, as defined heretofore.

FIG. 13 shows the next step in the molding sequence, in which the moldstarts to reform the case while the pressure of this reforming traps theexcess stock and begins unloading it through the mold taper instead ofpermitting it to flash out onto the case.

FIG. 14 shows the last step in the molding sequence, with the mold fullyclosed and the case permanently formed. In this view, broken linesindicate outer portions of a few of the many difierent sizes of casesthat may be used in this same mold, so long as they have the same sizeinner pierce.

FIG. 15 is a view similar to FIG. 14 but illustrating what happens whenthere is a minimum amount of load in the mold, much less than the normalaverage overload used.

FIG. 16 is a view similar to FIG. 15 indicating the result of applying alight extra overload, while FIG. 17 is a similar view in which there hasbeen a very heavy overload.

FIG. 18 is a view similar to a portion of FIG. 14, showing a mold for aseal like that of FIGS. 5 and 6.

The shaft seal 20 shown in FIGS. 1 and 2 is composed of four principalelements; a rigid metal outer case member 21, a rigid metal inner casemember 22, a resilient sealing member 23, and a garter spring 24. Thegarter spring 24 is not employed with every type of shaft seal and issometimes omitted (as, for example, in the seal shown in FIG. 8).

The outer case member 21 may be an integral annular member formed toprovide a radially extending annular portion or radial flange 25 and anouter cylindrical por- 7 tion or axial flange 26, which may fit into ahousing bore.

The axial flange 26 may, if desired, be formed with a radiallyprojecting portion 27 which serves a stop and guide function when placedinto the bore, although this is not always necessary or desirable.

The inner case member 22, used in many types of seals but not alwaysnecessary, may have an axially extending portion 28 nested into theaxial flange 26 of the outer case 21, and a radially extending portion29, and may be clamped into the outer case 21 by the turned-over edgeportion 30 at the inner case corner 31, with the end 32 of the axialportion 28 bearing against the radial flange 25.

A very important structural feature of the product of the presentinvention is the generally frusto-conical end portion 0 rtip 35 of theradial flange 25 to which the sealing member 23 is-bonded. This tip 35may be either at the inner periphery or pierce in an internal-type se(FIGS. 1-7), or at the outer periphery of an externaltype seal (FIG. 8),and the tip 35 may either be turned axially inwardly (FIGS. 1-6 and 8),or axially outwardly (FIG. 7). The important thing is that to that tipportion 35, and substantially to that portion only, is bonded the rubbersealing member 23.

As shown in FIG. 2 and FIG. 3, the anchorage of the sealing lip 23 isaccomplished by a generally radial or frusto-c'onical portion 36 bondedto the inner face 37 of the tip 35, a portion 38 bonded to the end edge39 (which may be very small, depending on the thickness of the metalused for the case member 21), and an outer portion 40 bonded to aportion 41 comprising part but not all of the outer face 42 of the tip35. The synthetic rubber which may be of any desired oil-resistant type,as known well in the art, stops sharply at points Y43 and 44,respectively, of the inner and outer faces. Note that the cutoff 43 liesright at the corner 45 where the tip 35' joins the radial portion 46 ofthe flange 25. Also note that the cutoff 44 lies between (approximatelyhalf way between) the edge 39 and the corner 45 on the outer face 42.How these sharp flashless cutofls are obtained will be explained alongwith the method, and it will then be clear What is accomplished. For thepresent, it will be noted that the sharp cutoff and the confining of therubber anchorage to the tip 35 gives adequate and accurate anchoring ofthe seal mem ber 23 without excess volume of materialand without flash,which would be objectionable. Substantial amounts of rubber are saved bythis method, while the very tight bond provides quite accurate holding.

The sealing lip 47 is easily obtained by one simple knife out along theline 48 in FIG. 3, cutting off the excess portion 49. This trimming isthe only operation after molding, due to the absence of flash from theseal 20.

A seal 50 shown in FIG. 4 is substantially like the seal 20 shown inFIGS. 1 through 3 and is made in substantially the same manner. It isillustrated principally to show the use of an outer case member 51 whichhas a stepped radial flange 52, showing that the flange need not beradial over its entire width. The step 53 between outer portion 54 andinner portion 55 does not aflfect the present invention; it is importantthat there be a radial portion like the portion 55, and a peripheralportion formed into a tapered or frusto-conical annular tip 35 (ateither the inner pierce or the outer periphery of the seal) to which thesealing member 23 is attached. The relative widths of the radial portionand peripheral portion are not important, except as hereinafter noted.

The seal 60 shown in FIGS. 5 and 6 has some special features andadvantages which should be noted; in addition, a simpler form of casemember 61 is shown, having an axial flange 62, a radial flange 63, and atip portion 64. The principal difference, however, is that its resilientsealing lip member 65 is provided with two lips, 66 and 67.

The lip 67 may be used for sealing tout dust rather than for fluidsealing, while the fluid is sealed by the lip 66. The lubricant-sealinglip 66 may be provided with a springreceiving cavity 68 to receive agarter spring 69, while the dust-sealing lip 67 requires no spring.

Independence of these two lips 66 and 67 from each other is a greatlydesired quality but one that is not easily obtained. However, thepresent invention does give this desired independence, because thedust-sealing lip 67 is on the opposite side of the in-turned,frusto-conical portion 64 from the fluid-sealing lip 66, and the dustlip 67 is backed up by and supported substantially directly by the tip64 and its lip base 70. A diaphragm-like web portion 71 connects thedust lip base 70 to the base 72 of the lubricant-sealing lip 66, whichis supported by a different part of the tip 64. As a result, anymovement of the springurged sealing lip 66 is not transmitted to thedust sealing lip 67, which is kept independent, and vice versa. Thisindependence is an important advantage of the present invention, whereit is easily obtained; whereas it was very diflicult and, in some cases,impossible to provide with prior art lip anchorages.

FIG. 6 shows the seal 60 as it comes from the mold. (See FIG. 18). Inthis instance, the sealing lip 66 is formed by trimming oif the excessportion 73 along the line 7-4, while the sealing lip 67 is formed bytrimming off the excess portion 75 along the line 76. Note that again,as in all forms of the invention, the larger portion 77 of the rubberanchor stops short at the corner 78. The other cutoff 79 again lies onthe outer face of the tip '64 intermediate its edge and the corner '7 8.

FIG. 7 shows a seal 80 having an outer case 81 enclosing two inner cases82 and 83. The inner case 82 has an axial flange 84 and a radial flange85, and a felt ring 86 is compressed between the flange 85 of the case82 and a radial flange 87 of the case 81. Because of this felt ring 86,the flange 85 is provided with a tip 88 bent in the opposite directionfrom the tips 35 and 64 described heretofore. In other words, asynthetic rubber sealing member 89 is to be provided and it cannot belocated where the felt ring 86 is to be. Therefore, the annular tip orfrusto-conical peripheral portion 88 is formed on the opposite side ofthe flange 85 from the flange 84 instead of on the same side, as inFIGS. l-6. This illustrates the flexibility of the invention.

An external-type seal 90 is shown in FIG. 8. Here the seal 90 has a case91 with a radial flange 92 extending radially outwardly from aradially-innercylindrical portion 93. The cylindrical portion 93 isadapted to be secured rigidly to a shaft for rotation therewith, whilethe housing bore is wiped by a sealing lip 94. The sealing member 95 isanchored to a frusto-conical peripheral portion or annular tip 96, asbefore, the only difference being that the tip 96 is at the outerperiphery of the case instead of at the inner periphery as in tips 35,64 and 88. External seals may have garter springs but, just for anexample, a springless seal has been shown. Note that the cutofl'T points97 and 98 are analogous to the cutoff points 43 and 44, the point 97lying at the corner 99 formed by the ti 96.

The foregoing examples illustrate the basic principles of the productaspects of the invention, but by no means exhaust its possibilities. Menskilled in the art will be quick to see how the invention applies inmany fields and to many types of seals, and will readily be able todesign further modifications, all coming within the scope of thisinvention. Certain other important product features will have to bedeferred until after a discussion of the method by which the product ispreferably made.

The method of the invention using my new closed stroke process will nowbe described. The molding sequence of the seal of this invention isshown in FIGS.

9 through 14. As will be seen, the mold used has two parts, a lowermold-half or block 100 and an upper moldhalf or die 101. The lower block100 is generally cylin- 6 drical with a periphery 102 from which extendsradially inwardly a seat 103. At the inner end of the seat 103 there isa short cylindrical portion 104 leading to a short shelf 105 adapted tosupport the inner periphery 106 of a case member 107. The shelf 105preferably is curved as shown and terminates in a cylindrical portion108 that leads to a taper portion 109 which aids in loading andcentering the case member 107 in the proper position,,but whose mainpurpose is the shaping of the sealing lip, as the portion 108 shapes theweb. Centering, however, is important since the outer periphery of thecase memher 107 lies outside the mold and is not used in centering.Before the molding operation begins, a suitable bonding cement isapplied to the case member by spraying, dipping, or other suitablemeans.

Above the tapered block portion 109 lies a generally radial platform 110on which the ring 11 of prep stock (any suitable elastomer) is placed.The radially inner end of the platform 110 joins a second taperedportion 112, which in turn ends at a central circular table portion 113.

The upper mold half or die 101 has a generally similar shape but by nomeans a matching one, since the mold is made to provide a proper cavityfor forming the clastomeric sealing lip 115. The die 101 is alsogenerally cylindrical, and its periphery is generally in line with theperiphery 102. The die 101 has adjacent its periphery 120 a narrowcircular rim 121 designed to engage the case and press it against thelower block 100 in a closed stroke, an action very important in thepresent invention. Radially inwardly of the rim 121 is the major cavityportion 122, of whatever shape is suitable, terminating in an extendedradial portion 123, part of which overlies the platform 110 and is thefirst portion to contact the prep ring 111. The inner end of the portion123 leads to a tapered portion 124 that lies opposite the taper 112. Theportion 124, in turn, leads to a toroidal trap 125 bounded on itsradially inner edge by a short annular rim 126. The die 101 is annularand has an inner periphery 127 surrounding a central cylindrical recess128.

In FIG. 9, the mold is open. The metal ring 107 rests on the shelf 105at its inner peripheral edge 106 only. The ring 111 of prep stock restson its platform 110. The mold is now ready to be closed.

In FIG. 10, the upper mold half or die 101 has been lowered part way. Itengages the prep stock 111 and begins to squeeze it. The mold is heated;so the stock will soon begin to flow, but at this point the prep stock111 is simply deformed a small amount and does not flow. Furtherdownward movement of the die 101 (FIG. 11) begins to force the stockdown into the mold cavity as it follows the path of least resistance, ascompared with the restricted path up between mold faces 112 and 124. Therubber, however, cannot flow fast enough to reach the case 107 beforethe die rim 121 does (FIG. 12). The rim 121 engages the case 107 aboutbefore the end of its stroke. In FIG. 12, the mold cavity is still notfilled.

Further downward movement of the die 101, as shown in FIG. 13, causesthe case 107 to reform, forming the frusto-conical portion or annual tip35. The pressure of forming at A and B (the opposite ends of the corner45 from which the tip 35 is bent) traps the flowing elastomer so that itcannot seep out and cause flash anywhere, as the bending forms thecorner 45. Now it can be seen why the cutoff at 43 and 44 is sharp andflashless and why it occurs where it does. The unit pressure at points Aand B may be upwards of 50,000 p.s.i., since the total force applied toclosing the mold is exerted on a very small area. Tests have shown thatno flash extrudes beyond points A and B even with severe overloading,due to these high unit pressures achieved. Any excess stock presentunloads upwardly from the platform 110 through the passage between thetapers 124 and 112, toroidal trap 125, and out between the portions 113and 7 126 to the recess 128. For normal loading, as shown in FIG. 14,the recess 128 will be only slightly filled. This is with an overload ofabout 15%, enough to insure complete filling of the moldcavity andprovide a low amount of rubber wastage.

As shown in FIG. 14, the last in the molding sequence, another featureof this invention is that various sizes of rings, 1107, 107a, 107b,107a, etc., may be used as long as the inner pierce 106 is the same. Inother words, with the same size shaft but different housings or bores, agreat variety of rings can be treated in the same mold and provided withsubstantially the same sealing member. This is a very important featureof the invention.

As shown in FIG. 15, even if the mold is substantially underloaded, thecavity where the lip is formed will be completely filled because of thegreat pressure placed on the prep. There, the rubber filled the mold butbarely sent a littlerubber up between tapers 112 and 124 into the trap125.

As shown in FIGS. 16 and 17, there is no flash past points A and B, evenwith severe overloading, but the excess stock flows into the recess 128.In fact, tests have shown that until the entire recess 128 is filled andthe rubber has nowhere else to flow, there will be no movement pastpoints A and B. In order to get such movement it was found in tests thatoverloads of 10% or more had to be applied which, of course, is farbeyond what would be encountered in manufacture.

FIG. 18 shows how a seal 60 (see FIGS. and 6) may be molded. While onlya portion of the mold is shown, the other parts are like those describedand shown in FIGS. 9 through 14. In fact, the upper mold half 101 may bethe same as that already described. The lower mold half 1130 ispreferably made up of two elements 131 and 132, because of there-curving of the dust lip portion 70. In this instance, the formationof the lower mold half 130 is nevertheless substantially the same asthat of the element 100 except forthe provision of a dust lip moldingcavity 133 bounded by the two mold portions 131 and 132. Again, thecorners A and B are used to provide the forming pressure, though thearea of the corner B in this example is shown somewhat larger than inFIGS. 9 through 14. This is possible because in this instance theterminal portion 64 is bent out at a larger angle approximately 45.

It should be noted that, in the invention as a whole, an importantfeature is the. provision of a closed stroke mold operation to insurethat both the upper and lower mold halves contact the metal insertbefore the mold is completely closed. The closed stroke is achieved, asdescribed, by deforming the metal insert. It has been found by tests,practical experience, and theoretical calculations that the minimumpractical deformation is approximately 0.015 deformation of the end edgefrom the fiat. In other words, the periphery is lifted at least 0.015above the plane of the radial flange, and this means that each point onthe edge is lifted at least that far above the plane of its previoussurface. The upper limit of deformation depends solely on the sealdesign. It may be 0.200 or higher.

The radial width of the deformed portion may vary over relatively widelimits, once deformation of at least 0.015" has been achieved. It may bevery narrow or it may be very wide, though for the best practicalresults neither the narrowest nor the widest feasible limits are ideal,and the drawings give a good indication of desirable proportioning. Theminimum radial distance between points A and B will depend upon themetal thickness and the actual amount of deformation being used. Theupper point A must be at a greater radius from the center than the lowerpoint B; otherwise, the line of action of the force applied would bethrough the same point, not allowing deformation of the metal andtherefore not achieving a closed stroke.

Once the conditions of the preceding paragraphs'have been met, there isa wide field for variation Within the scope of this invention, and whatis preferable in one instance may not be preferable in another instance.For example, the point B may lie at any location between the actualperipheral edge of the finished seal and the corner about which it isturned, so long as the preceding conditions are fulfilled. It ispossible to have the point B actually at the peripheral edge, but it isdifficult, due to engineering and manufacturing tolerances, to beassured of control when the apparatus is designed for such closecontact. For that reason, it is better to have the point B in betweenthe point A and the peripheral edge. Similarly, it is better to have thepoint B not lie too close to the corner, for the same general reasons,and also to insure proper length of the closed stroke by having thepoint B lie enough above the shelf 103 to insure a closed stroke. Theamount of rubber which is bonded between the point B and the peripheraledge, as in the position 40, is not of critical importance in practicingthe method, though for any practical product one distance may be betterthan another.

It is not absolutely necessary that the metal be deformed beyond itselastic limit in the tip portion. It is possible to practice the methodwith a closed stroke within the elastic limit, so that the metal aftermolding returns to its original flat radial position. However, it isdefinitely preferable that the deformation be permanent and that theelastic limit be passed, because this gives greatly improved dimensionalstability and will produce a much better appearing product.

As has been stated earlier, the amount of deformation is of moreimportance than the angle of deformation, but this does not mean thatthe angle itself is not important. Even with products lying within thescope of the invention, there are some that utilize the invention in itsbest and most practical form. While a relatively small angle will obtainsome of the advantages of the invention, at least to a degree, theadvantages are not generally fully obtained in a seal having a narrowtip, nor does the finished seal have a fully satisfactory appearanceuntil the metal has been deformed at an angle of about 25 or greater,and in fact, an angle of 30 is preferably employed. Moreover, the widthof the tip should not be too great if economy in the. amount of rubberused for bonding is to be obtained. There is also a practical maximumlimit of angle for most'applications of the invention, due to the effectthat the bending has, at angles greater than 45, of pulling the innerpierce too far away from the shaft, and so a practical maximum ofbending normally lies around 50. Thisdoes not mean that seals cannot bemade having extended molded portions to make up for the bending of thetip end portion, but it does mean that the best support for the sealingelement is obtained in an angle less than 50. In other words, dimensional stability, economy used in the amount of rubber used in thebonding, and assurance of a closed stroke will usually combine to set alower limit of 25, although bending below that amount does not normallyaffect the sealing function of the device as such. On the other hand,above 50 the sealing function may be affected, as well as the economy ofthe material and greater angles import some compensation elsewhere if asatisfactory seal is to be applied. Thus, the range betweenapproximately 25 and 50 is considered to encompass the preferableembodiment of the invention, with the range between 30 and 45 giving thebest results of all.

The foregoing paragraphs distinguish the present invention fromdisclosures where the portion immediately adjacent the periphery is bentvery slightly, reforming only the bare peripheral portion, if anything,in order to cut off the molded rubber at the peripheral edge instead ofpermitting it to flow along the edge and engage the outer edge of thereinforcing ringas it does in this invention.

Economy in tooling results from the fact that the upper and lower piecesof the mold are the only mold parts needed, since the outside diameterof the mold is not affected by the outside diameter of the case member.Case members of varying radial extent may be used so long as thepierces, the periphery to which the sealing portion is applied, areidentical, and the same mold is used regardless of which radial face ofthe flange the rubber is bonded to. Alternatively, it is possible withmolds of this type to provide more cavities per unit area in amulticavity mold, since there is no need to confine the outer peripheryof the case and, since the case lies outside the mold proper, the casesobviously can be closer to each other than they could be where a moldpart had to be in between them. Also, there is more tooling capacity perthe amount of money spent on the mold, resulting in more production atlower cost, because of the convenience and ease of insertion of theparts. The fact is, a better quality of mold is obtained because of thesmaller less complex mold area, which can be given more carefulattention and can be cleaned and maintained more easily than can moldswhere the cavities are more complex or are larger. The elimination offlash also supplies another reason why the mold is easier to maintain,is easier to clean, and must be polished less often.

The location feature which has been referred to is another veryimportant advantage of this invention. Concentricity is assured so longas the inner pierce itself is properly made, since the pierce absolutelylocates the case in the mold.

To those skilled in the art to which this invention relates, manyadditional changes in construction and widely differing embodiments ofthe invention will suggest themselves without departing from the spiritand scope of the invention as defined in the claims.

What is claimed is:

1. A method for fiashless molding and simultaneous bonding of anelastomeric sealing lip for a shaft seal, to an annular metal caseelement having a radial portion with opposite radial faces and anaxially extending peripheral edge extending between the faces, whichcomprises supporting said element only about the peripheral marginalportion of one radial face thereof, applying axial pressure to theopposite face of the element in a circular line radially spaced from theperipheral marginal portion to move the body of the case elementrelative to the marginal portion against a seat member to therebyprovide a marginal flange portion bent at an obtuse angle to the otherradial face, simultaneously applying elastomeric material against theexposed surface of the case element extending between the line at whichthe pressure is being applied and the support for the marginal portionon the other face of the case element, and bonding the elastomericmaterial to the case element without flash by the applied axialpressure.

2. A method for fiashless molding and simultaneous bonding of an annularelastomeric sealing lip for a shaft seal, to an annular metal caseelement having a radial portion with two opposite radial faces and anaxial peripheral edge extending between the faces, comprising axiallyapplying pressure in one direction to one face of the case element in acircular line radially displaced from the peripheral edge to seat theopposite face of the case element against an underlying support, axiallyapplying pressure in the opposite direction to the other face of thecase element in a second circular line between the first-named circularline and the periphery to provide a marginal flange bent at an obtuseangle relative to the first radial face, applying elastomeric materialto both faces of the case element at an area extending between the twopressure zones, and bonding the elastomeric material to the case elementwithout flash by the applied axial pressure.

3. A method for fiashless molding and simultaneous bonding of anelastomeric sealing lip for a shaft seal, to an annular metal caseelement having a generally radial portion with opposite faces and anaxially extending peripheral edge extending between the faces, whichcomprises centering said case element with one face on a hollow annularsupport of lesser diameter than the case element, applying axialpressure to the other face of the case element in a circular lineconcentric with and radially spaced from the annular support to move thecentral portion of the element until the peripheral margin is bent awayfrom the plane of the annular support at an obtuse angle to the centralportion of the element, applying elastomeric material to the face of theelement between said circular line and the periphery simultaneously withthe initial application of the axial pressure, and bonding theelastomeric material to the case element without flash between saidcircular line and the annular support and about the periphery uponcontinued application of the axial pressure to produce the bentperipheral margin.

4. A method for fiashless molding and simultaneous bonding of an annularelastomeric sealing lip for a shaft seal, to an annular metal caseelement having a radial portion with two opposite radial faces and anaxial peripheral edge extending between the faces, comprising axiallyapplying pressure in one direction to one face of the case element in acircular line radially displaced from the peripheral edge to seat theopposite face of the ease element against a parallely extendingunderlying support, axially applying pressure in the opposite directionto the other face of the case element in a second circular line betweenthe first-named circular line and the periphery to provide a marginalflange bent at an angle relative to the first radial face, applyingelastomeric material to both faces of the case element at an areaextending between the two pressure zones, and bonding the elastomericmaterial to the case element without flash by the applied axialpressure.

5. A method for fiashless molding and simultaneous bonding of anelastomeric sealing lip for a shaft seal, to a rigid annular metal caseelement having a radially extending portion with opposite faces andhaving inner and outer peripheries which comprises, applying pressure inone direction against one face of the element in a circular lineadjacent one of said peripheries and simultaneously applying pressure inthe opposite direction against the opposite face of the element in aconcentric circular line radially spaced from the one periphery toproduce an annular peripheral margin bent at an angle to the radiallyextending portion, applying elastomeric material against the exposedsurface of the case element extending between the pressure Zones andbonding the elastomeric material to the case element without flash bythe applied axial pressure.

References Cited in the file of this patent UNITED STATES PATENTS2,146,677 Johnson Feb. 7, 1939 2,145,928 Heinze et al. Feb. 7, 19392,700,186 Stover Jan. 25, 1955 2,772,012 Crabtree Nov. 27, 1956 FOREIGNPATENTS 1,046,916 France Dec. 9, 1953

